Solve for $x$ and $y$ using substitution. ${2x+5y = -4}$ ${x = -4y-5}$
Answer: Since $x$ has already been solved for, substitute $-4y-5$ for $x$ in the first equation. ${2}{(-4y-5)}{+ 5y = -4}$ Simplify and solve for $y$ $-8y-10 + 5y = -4$ $-3y-10 = -4$ $-3y-10{+10} = -4{+10}$ $-3y = 6$ $\dfrac{-3y}{{-3}} = \dfrac{6}{{-3}}$ ${y = -2}$ Now that you know ${y = -2}$ , plug it back into $\thinspace {x = -4y-5}\thinspace$ to find $x$ ${x = -4}{(-2)}{ - 5}$ $x = 8 - 5$ ${x = 3}$ You can also plug ${y = -2}$ into $\thinspace {2x+5y = -4}\thinspace$ and get the same answer for $x$ : ${2x + 5}{(-2)}{= -4}$ ${x = 3}$